This invention relates to a device suitable for mechanically controlling by means of a foot control pedal the engagement of the speed gears in a traditional type of automotive transmission, i.e. one originally intended for hand lever control.
It is generally agreed that it may become necessary or at least advantageous to convert the manual control of a motor vehicle transmission for pedal control, for example in those instances wherein it is preferable or even necessary not to have one hand occupied to operate the transmission gear shift control, either when a car controls are to be adapted for operation by drivers with partly disabled limbs, or more particularly, to pedal control the transmission of a motorbike equipped with an automotive type of transmission, e.g. on motorbikes propelled by an automotive type of engine-drive combination.
It is known that automotive transmissions are generally provided, when such transmissions comprise no more than four speeds including reverse, or are applied to motorbikes where the reverse gear speed is usually omitted, with a control system essentially comprised of: (a) a speed selecting mechanism which is shiftable between two positions, at each whereof two speeds may be selected; (b) a speed engaging mechanism capable of occupying three different positions, namely: drive-neutral-drive, i.e. effective to engage one of two speeds for each of the two positions of the selecting mechanism mentioned under (a) above.
Said selecting and engaging mechanisms are usually operated, in the automotive type of transmission, by acting either through two discrete control stations, a selecting one and an engaging one, or through a single control assembly performing both functions and which, with one movement, brings into operation said selecting mechanism, and with another movement, different from the previous one (e.g. with a rotational movement, whereas the former may be a linear motion type of movement), causes said engaging mechanism to become operative.
Therefore, in order to pedal control an automotive type of transmission, a device is required which is capable of effecting two discrete movements, one to be independent of the other, to differentially actuate said speed selecting and engaging mechanisms. The design problems are further aggravated by the necessity of providing a much simplified device, if it is to be really practical, featuring a high degree of sensitivity and operational reliability, and moreover, a highly compact design. Furthermore, such a device should, in order to be competitive, require foot control movements which are quite similar to those required by the pedal-controlled transmissions currently employed on motorbikes.